Fix Performance/Sum cop (#24788)

.rubocop_todo.yml

@@ -371,14 +371,6 @@ Performance/StartWith:
   Exclude:
     - 'app/lib/extractor.rb'
 
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: OnlySumOrWithInitialValue.
-Performance/Sum:
-  Exclude:
-    - 'app/lib/activity_tracker.rb'
-    - 'app/models/trends/history.rb'
-    - 'lib/paperclip/color_extractor.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 Performance/TimesMap:
   Exclude:

app/lib/activity_tracker.rb

@@ -43,7 +43,7 @@ class ActivityTracker
 
     case @type
     when :basic
-      redis.mget(*keys).map(&:to_i).sum
+      redis.mget(*keys).sum(&:to_i)
     when :unique
       redis.pfcount(*keys)
     end

app/models/trends/history.rb

@@ -11,7 +11,7 @@ class Trends::History
     end
 
     def uses
-      with_redis { |redis| redis.mget(*@days.map { |day| day.key_for(:uses) }).map(&:to_i).sum }
+      with_redis { |redis| redis.mget(*@days.map { |day| day.key_for(:uses) }).sum(&:to_i) }
     end
 
     def accounts

lib/paperclip/color_extractor.rb

@@ -173,7 +173,7 @@ module Paperclip
     def palette_from_histogram(result, quantity)
       frequencies       = result.scan(/([0-9]+)\:/).flatten.map(&:to_f)
       hex_values        = result.scan(/\#([0-9A-Fa-f]{6,8})/).flatten
-      total_frequencies = frequencies.reduce(&:+).to_f
+      total_frequencies = frequencies.sum.to_f
 
       frequencies.map.with_index { |f, i| [f / total_frequencies, hex_values[i]] }
                  .sort_by { |r| -r[0] }